The invention relates to a manufacturing system in the form of a bending press or folding press, as well as to a method for operating such a manufacturing system.
A folding press with a manipulating device and a method for the automated folding of sheets of metal are known from document EP 0 914 879 A1. The manipulating device is adjustable in this connection on a chassis in the direction of the longitudinal expanse of the folding beams, and equipped with gripping devices for picking up and feeding the sheets of metal and for folding the latter between the folding dies. Provision is made for sensors for correctly positioning the sheets of metal and for controlling the correct position of the sheets of metal, and the folding process is controlled by means of the signals of said sensors.
A method and a device for inserting workpieces between the folding dies of a folding press with a manipulating device and with sensor-controlled adjustment of the position and control of the position of the workpiece are known from document U.S. Pat. No. 5,761,940 A. According to said method, and by means of the device inserting the workpiece for a folding operation, provision is made on the folding press for measuring systems equipped with pressure sensors, which are adjustable on a backside of the folding dies in at least two coordinate directions, and each provided with a scanning pin for resting against a stop edge of the workpiece. For positioning the workpiece, provision is made for at least two of such measuring systems, with scanning pins spaced from each other in the direction of the longitudinal expanse of the folding dies for scanning the stop edge of the workpiece, which is driven against the scanning pins for resting against the latter. Each measuring system is fitted with a sensor measuring the force, which is acted upon by the scanning pin via a lever arrangement, and the force with which the workpiece and any deviation from an intended position preset by the scanning pins are detected in this way, so that the position of the workpiece is corrected by means of the manipulating device if the measured values differ, until identical measured values are present on the measuring systems, and thus a position of the stop edge preset with respect to the folding plane is obtained, and reshaping of the workpiece by folding can thus be carried out on the workpiece with the latter in the correct position. The adjustment and control process requires high mechanical as well as controlling and regulating expenditure for the positioning process executed by the manipulating device.
A folding press that can be operated by a manipulator for a sheet folding process, and a method for positioning the sheet before it is inserted between the folding dies, are known from document U.S. Pat. No. 4,706,491 A. According to said document, a fixed stop is provided on the folding press on the front side, and the sheet is placed against said stop, whereby said stop is forming a reference position for the displacement of the manipulator for adjustments.
For feeding workpieces to a folding press by means of a manipulator, a detector device mounted on the manufacturing system is known from AT 402 372 B. The position of an edge of the workpiece with respect to parallelism in relation to a working plane is measured by means of said detector device, and if an angular position is detected to have occurred, readjustment is carried out by the manipulator. Based on the reference position so determined, the subsequent folding operations are carried out by computing the position and repositioning. The accelerative forces occurring as the workpiece is being driven into the folding position may cause the workpiece to be displaced in the gripping system when it is finally positioned between the folding dies, which may cause inaccuracies in the course of the folding process as well.